A standard long-wall mining machine such as described in my copending application attorney's 19560 has a scraper conveyor that extends horizontally parallel to the face being worked. A guide beam is fixed to the face side of the conveyor and is formed with an upwardly open slot in which is seated a longitudinally shiftable drive chain. A coal plow or the like rides on the rail and has a drive sprocket meshing with the chain. This plow scrapes ore or coal from the face and deposits it in the conveyor.
The standard chain is a simple round-link chain that rides in a cruciform-section upwardly open slot in the guide rail. The teeth of the drive wheel of the mining machine engage in the horizontal chain links, which are held in confronting horizontally open grooves of the guide rail. These teeth must therefore be relatively large and relatively widely spaced, even when as is common the horizontal links are long and the vertical ones short.